title: Lactate formation from [U-13C]aspartate in cultured astrocytes: compartmentation of pyruvate metabolism.
abstract: Metabolism of [U-13C]aspartate in cultured astrocytes and the effects of inhibitors of malic enzyme and phosphoenolpyruvate carboxykinase (hydroxymalonate and 3-mercaptopicolinic acid, respectively) were studied using 13C nuclear magnetic resonance (NMR) spectroscopy. The labelling of glutamate and glutamine showed entry of aspartate into the tricarboxylic acid (TCA) cycle after conversion to oxaloacetate. Production of [U-13C]pyruvate from [U-13C]aspartate was revealed by the presence of [U-13C]lactate in incubation media. Furthermore, labelling patterns in C-2 and C-3 in intracellular aspartate showed entry of [1,2-13C]acetyl-CoA into the TCA cycle; evidence for pyruvate-recycling. No reduction in [U-13C]lactate was observed in the presence of either enzyme inhibitor. However, 3-mercaptopicolinic acid reduced incorporation of labelled acetyl-CoA into TCA cycle intermediates, indicating compartmentation of pyruvate production in astrocytes.
authors.affiliation: Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim.
authors.forename: I J
authors.initials: IJ
authors.lastname: Bakken
authors.forename: L R
authors.initials: LR
authors.lastname: White
authors.forename: J
authors.initials: J
authors.lastname: Aasly
authors.forename: G
authors.initials: G
authors.lastname: Unsgård
authors.forename: U
authors.initials: U
authors.lastname: Sonnewald
mesh_terms: D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D001253:Astrocytes / Q000201:enzymology / Q000378:metabolism*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007150:Immunohistochemistry; D019344:Lactic Acid / Q000096:biosynthesis*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000037:antagonists & inhibitors / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D001224:Aspartic Acid; D019344:Lactic Acid; D019289:Pyruvic Acid; D019764:Phosphoenolpyruvate Carboxykinase (ATP)